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XML反序列化器中的奇怪行爲

2011-02-02 51 views
0

在使用SAX時，我在Java中出現了一些奇怪的行爲。正在設置值，但在輸出的toString方法中恢復爲默認值。這看起來很不尋常。我查看了代碼並輸出了變量的內存地址，並且所有事情都以正確的順序進行，看起來是正確的。其他反序列化的XML元素很好，所以我無法解決這個問題。XML反序列化器中的奇怪行爲

我的系統的工作方式如下：有用戶定義屬性助手和元素處理程序的抽象方法的類。元素處理程序根據子XML元素處理子類的生成，而屬性handers從構造函數中獲取屬性列表，並通過屬性助手使用屬性列表通過屬性幫助器中已實現的抽象方法設置字段。

這裏所討論的問題類：

package kokuks.flowmon; 

import kokuks.flowmon.FlowmonParser.Handler; 

import org.xml.sax.Attributes; 

public class FlowProbeFlowStats extends FlowmonParserElement { 
    protected final FlowProbe parent; 
    protected int flowId = 0; 
    protected int packets = 0; 
    protected int bytes = 0; 
    protected long delayFromFirstProbeSum = 0; 
    protected boolean set = false; 

    /** 
    * @param handler 
    * @param parent 
    * @param uri 
    * @param localName 
    * @param qName 
    * @param attributes 
    */ 
    FlowProbeFlowStats(Handler handler, FlowProbe parent, String uri, String localName, String qName, Attributes attributes) { 
     super(handler, parent, uri, localName, qName, attributes); 
     this.parent = parent; 
    } 

    /** 
    * @return the parent 
    */ 
    public FlowProbe getParent() { 
     return parent; 
    } 

    /* (non-Javadoc) 
    * @see kokuks.flowmon.FlowmonParserElement#getXMLName() 
    */ 
    @Override 
    protected String getXMLName() { 
     return "FlowStats"; 
    } 

    /* (non-Javadoc) 
    * @see kokuks.flowmon.FlowmonParserElement#createAttributeHandlers() 
    */ 
    @Override 
    protected IAttributeHandler[] createAttributeHandlers() { 
     return new IAttributeHandler[] { 
      new AttributeHandler("flowId") { 
       @Override 
       public void perform(String argValue) { 
        System.out.println("AH flowId: " + argValue); 
        flowId = Integer.parseInt(argValue); 
        set = true; 
       } 
      }, 
      new AttributeHandler("packets") { 
       @Override 
       public void perform(String argValue) { 
        System.out.println("AH packets: " + argValue); 
        packets = Integer.parseInt(argValue); 
        set = true; 
       } 
      }, 
      new AttributeHandler("bytes") { 
       @Override 
       public void perform(String argValue) { 
        System.out.println("AH bytes: " + argValue); 
        bytes = Integer.parseInt(argValue); 
        set = true; 
       } 
      }, 
      new AttributeHandler("delayFromFirstProbeSum") { 
       @Override 
       public void perform(String argValue) { 
        System.out.println("AH delayFromFirstProbeSum: " + argValue); 
        delayFromFirstProbeSum = Long.parseLong(argValue.substring(0, argValue.length() - 2)); 
        set = true; 
       } 
      } 
     }; 
    } 

    /* (non-Javadoc) 
    * @see java.lang.Object#toString() 
    */ 
    @Override 
    public String toString() { 
     return "FlowStats/" + super.toString() + "[flowId: " + flowId + ", packets: " + packets + 
     ", bytes: " + bytes + ", delayFromFirstProbeSum: " + delayFromFirstProbeSum + "]"; 
    } 
}

我也有一些調試輸出，其中屬性擡頭一看，所謂的相關實現的方法。

if (this instanceof FlowProbeFlowStats) { 
     System.out.println("ahaaaa1:: " + this.toString()); 
    } 

    IAttributeHandler[] ahandlers = createAttributeHandlers(); 

    if (ahandlers != null) { 
     Map<String, IAttributeHandler> attributeHandlers = new HashMap<String, IAttributeHandler>(ahandlers.length); 
     for (IAttributeHandler ah : ahandlers) { 
      attributeHandlers.put(ah.getName(), ah); 
     } 

     for (int i = 0; i < attributes.getLength(); i++) { 
      IAttributeHandler ah = attributeHandlers.get(attributes.getQName(i)); 
      if (ah == null) { 
       throw new IllegalStateException("Attribute helper not found in qName: " + qName + " for attrib with localName: " + attributes.getLocalName(i) + ", qname*: " + attributes.getQName(i)); 
      } 

      try { 
       ah.perform(attributes.getValue(i)); 
      } catch (Exception e) { 
       e.printStackTrace(); 
      } 
     } 
    } 

    if (this instanceof FlowProbeFlowStats) { 
     System.out.println("ahaaaa2:: " + this.toString()); 
    }

無論如何，這裏是輸出：

ahaaaa1:: FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0] 
AH flowId: 1 
AH packets: 5 
AH bytes: 333 
AH delayFromFirstProbeSum: 50274395ns 
ahaaaa2:: FlowStats/[email protected][flowId: 1, packets: 5, bytes: 333, delayFromFirstProbeSum: 50274395] 
ahaaaa1:: FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0] 
AH flowId: 2 
AH packets: 5 
AH bytes: 333 
AH delayFromFirstProbeSum: 50274395ns 
ahaaaa2:: FlowStats/[email protected][flowId: 2, packets: 5, bytes: 333, delayFromFirstProbeSum: 50274395] 
ahaaaa1:: FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0] 
AH flowId: 3 
AH packets: 5 
AH bytes: 1082 
AH delayFromFirstProbeSum: 0ns 
ahaaaa2:: FlowStats/[email protected][flowId: 3, packets: 5, bytes: 1082, delayFromFirstProbeSum: 0] 
ahaaaa1:: FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0] 
AH flowId: 4 
AH packets: 4 
AH bytes: 762 
AH delayFromFirstProbeSum: 0ns 
ahaaaa2:: FlowStats/[email protected][flowId: 4, packets: 4, bytes: 762, delayFromFirstProbeSum: 0] 
ahaaaa1:: FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0] 
AH flowId: 2 
AH packets: 5 
AH bytes: 333 
AH delayFromFirstProbeSum: 0ns 
ahaaaa2:: FlowStats/[email protected][flowId: 2, packets: 5, bytes: 333, delayFromFirstProbeSum: 0] 
ahaaaa1:: FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0] 
AH flowId: 4 
AH packets: 4 
AH bytes: 762 
AH delayFromFirstProbeSum: 40615996ns 
ahaaaa2:: FlowStats/[email protected][flowId: 4, packets: 4, bytes: 762, delayFromFirstProbeSum: 40615996] 
ahaaaa1:: FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0] 
AH flowId: 1 
AH packets: 5 
AH bytes: 333 
AH delayFromFirstProbeSum: 0ns 
ahaaaa2:: FlowStats/[email protected][flowId: 1, packets: 5, bytes: 333, delayFromFirstProbeSum: 0] 
ahaaaa1:: FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0] 
AH flowId: 3 
AH packets: 5 
AH bytes: 1082 
AH delayFromFirstProbeSum: 51335996ns 
ahaaaa2:: FlowStats/[email protected][flowId: 3, packets: 5, bytes: 1082, delayFromFirstProbeSum: 51335996] 
[kks-j~KokuKS~/Names] fmxml:FlowMonitor[FlowStats[Flow[flowID: 1,timeFirstTxPacket: 1011735011,timeLastTxPacket: 1343457103,timeFirstRxPacket: 1021768610,timeLastRxPacket: 1353490702,delaySum: 50274395,jitterSum: 212800,lastDelay: 10033599,txBytes: 333, rxBytes: 333,txPackets: 5,rxPackets: 5,lostPackets: 0,timesForwarded: 0],Flow[flowID: 2,timeFirstTxPacket: 1015259481,timeLastTxPacket: 1543226881,timeFirstRxPacket: 1025293080,timeLastRxPacket: 1553260480,delaySum: 50274395,jitterSum: 212800,lastDelay: 10033599,txBytes: 333, rxBytes: 333,txPackets: 5,rxPackets: 5,lostPackets: 0,timesForwarded: 0],Flow[flowID: 3,timeFirstTxPacket: 1021768610,timeLastTxPacket: 1332941904,timeFirstRxPacket: 1031802209,timeLastRxPacket: 1343457103,delaySum: 51335996,jitterSum: 481600,lastDelay: 10515199,txBytes: 1082, rxBytes: 1082,txPackets: 5,rxPackets: 5,lostPackets: 0,timesForwarded: 0],Flow[flowID: 4,timeFirstTxPacket: 1025293080,timeLastTxPacket: 1332969282,timeFirstRxPacket: 1035326679,timeLastRxPacket: 1343226881,delaySum: 40615996,jitterSum: 291200,lastDelay: 10257599,txBytes: 762, rxBytes: 762,txPackets: 4,rxPackets: 4,lostPackets: 0,timesForwarded: 0]],Ipv4FlowClassifier[Flow[flowId: 4, sourceAddress: 10.1.0.1, destinationAddress: 10.1.0.2, protocol: 6],Flow[flowId: 3, sourceAddress: 10.1.0.1, destinationAddress: 10.1.1.2, protocol: 6],Flow[flowId: 2, sourceAddress: 10.1.0.2, destinationAddress: 10.1.0.1, protocol: 6],Flow[flowId: 1, sourceAddress: 10.1.1.2, destinationAddress: 10.1.0.1, protocol: 6]],FlowProbes[FlowProbe[index: 0, stats: <FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0],FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0],FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0],FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0]>],FlowProbe[index: 1, stats: <FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0],FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0]>],FlowProbe[index: 2, stats: <FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0],FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0]>]]]

注意內存值 - 這是相當奇怪的。整個toString輸出（來自已轉換的根元素）位於最後一行。

無論如何，感謝您的幫助，
克里斯

編輯：設置在

protected final FlowProbe parent; 
protected int flowId = 1000; 
protected int packets = 1000; 
protected int bytes = 1000; 
protected long delayFromFirstProbeSum = 1000; 
protected boolean set = false;

這裏是結果：我設置的變量，而不是一些不同的默認值0

ahaaaa1:: FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0] 
[email protected]: AH flowId: 4 
[email protected]: AH packets: 5 
[email protected]: AH bytes: 1082 
[email protected]: AH delayFromFirstProbeSum: 0ns 
ahaaaa2:: FlowStats/[email protected][flowId: 4, packets: 5, bytes: 1082, delayFromFirstProbeSum: 0]

因此，最初有些奇怪的事情發生，值是0而不是1000.非常奇怪。當涉及到最終輸出時，正在輸出的對象的值爲1000而不是0（來自字段默認值的初始值）。

EDIT2：我現在有標頭中的以下內容：

protected int countdown = 4;

當屬性被設定，它遞減。一個例子是：現在

 new AttributeHandler("packets") { 
      @Override 
      public void perform(String argValue) { 
       synchronized (FlowProbeFlowStats.this) { 
        System.out.println(FlowProbeFlowStats.super.toString() + ": AH packets: " + argValue); 
        packets = Integer.parseInt(argValue); 
        System.out.println("packets set to " + packets); 
        set = true; 
        countdown--; 
       } 
      } 
     },

的oString聲明：

/* (non-Javadoc) 
* @see java.lang.Object#toString() 
*/ 
@Override 
public String toString() { 
    return "FlowStats/" + super.toString() + "[flowId: " + flowId + ", packets: " + packets + 
    ", bytes: " + bytes + ", delayFromFirstProbeSum: " + delayFromFirstProbeSum + 
    ", countdown: " + countdown + "]"; 
}

和打印輸出閱讀：

ahaaaa2:: FlowStats/[email protected][flowId: 1, packets: 5, bytes: 333, delayFromFirstProbeSum: 0, countdown: -4] 

... 

[kks-j~KokuKS~/Names] fmxml:FlowMonitor[FlowStats[Flow[flowID: 1,timeFirstTxPacket: 1007829288,timeLastTxPacket: 1524157706,timeFirstRxPacket: 1017862887,timeLastRxPacket: 1534191305,delaySum: 50274395,jitterSum: 212800,lastDelay: 10033599,txBytes: 333, rxBytes: 333,txPackets: 5,rxPackets: 5,lostPackets: 0,timesForwarded: 0],Flow[flowID: 2,timeFirstTxPacket: 1010210025,timeLastTxPacket: 1324387511,timeFirstRxPacket: 1020243624,timeLastRxPacket: 1334421110,delaySum: 50274395,jitterSum: 212800,lastDelay: 10033599,txBytes: 333, rxBytes: 333,txPackets: 5,rxPackets: 5,lostPackets: 0,timesForwarded: 0],Flow[flowID: 3,timeFirstTxPacket: 1017862887,timeLastTxPacket: 1313900107,timeFirstRxPacket: 1027896486,timeLastRxPacket: 1324157706,delaySum: 40615996,jitterSum: 291200,lastDelay: 10257599,txBytes: 762, rxBytes: 762,txPackets: 4,rxPackets: 4,lostPackets: 0,timesForwarded: 0],Flow[flowID: 4,timeFirstTxPacket: 1020243624,timeLastTxPacket: 1313872312,timeFirstRxPacket: 1030277223,timeLastRxPacket: 1324387511,delaySum: 51335996,jitterSum: 481600,lastDelay: 10515199,txBytes: 1082, rxBytes: 1082,txPackets: 5,rxPackets: 5,lostPackets: 0,timesForwarded: 0]],Ipv4FlowClassifier[Flow[flowId: 4, sourceAddress: 10.1.0.1, destinationAddress: 10.1.0.2, protocol: 6],Flow[flowId: 3, sourceAddress: 10.1.0.1, destinationAddress: 10.1.1.2, protocol: 6],Flow[flowId: 2, sourceAddress: 10.1.0.2, destinationAddress: 10.1.0.1, protocol: 6],Flow[flowId: 1, sourceAddress: 10.1.1.2, destinationAddress: 10.1.0.1, protocol: 6]],FlowProbes[FlowProbe[index: 0, stats: <FlowStats/[email protected][flowId: 1000, packets: 1000, bytes: 1000, delayFromFirstProbeSum: 1000, countdown: 4],FlowStats/[email protected][flowId: 1000, packets: 1000, bytes: 1000, delayFromFirstProbeSum: 1000, countdown: 4],FlowStats/[email protected][flowId: 1000, packets: 1000, bytes: 1000, delayFromFirstProbeSum: 1000, countdown: 4],FlowStats/[email protected][flowId: 1000, packets: 1000, bytes: 1000, delayFromFirstProbeSum: 1000, countdown: 4]>],FlowProbe[index: 1, stats: <FlowStats/[email protected][flowId: 1000, packets: 1000, bytes: 1000, delayFromFirstProbeSum: 1000, countdown: 4],FlowStats/[email protected][flowId: 1000, packets: 1000, bytes: 1000, delayFromFirstProbeSum: 1000, countdown: 4]>],FlowProbe[index: 2, stats: <FlowStats/[email protected][flowId: 1000, packets: 1000, bytes: 1000, delayFromFirstProbeSum: 1000, countdown: 4],FlowStats/[email protected][flowId: 1000, packets: 1000, bytes: 1000, delayFromFirstProbeSum: 1000, countdown: 4]>]]]

在屬性的setter和toString同步的聲明是這裏查看對於JVM的錯誤，但它沒有做任何事情。奇怪的呃？

編輯3：

我將字段更改爲原子*。我必須認真地把它歸結爲一個JVM的錯誤，看到原子字段是最終的，並在內部默認值設置，我得到一個NullPointerException。

protected final AtomicInteger flowId = new AtomicInteger(); 
protected final AtomicInteger packets = new AtomicInteger(); 
protected final AtomicInteger bytes = new AtomicInteger(); 
protected final AtomicLong delayFromFirstProbeSum = new AtomicLong();

例外：

Exception in thread "FlowMonitor Updater" java.lang.NullPointerException 
    at kokuks.flowmon.FlowProbeFlowStats.toString(FlowProbeFlowStats.java:95)

編輯4：我從JDK1.7改爲1.6，同樣的問題，一個穩定的版本。

我剛剛想過，也許這些字段 - 在構造函數期間未設置，然後再設置。我不確定初始化的順序，但在這種情況下可能會搞砸了。無論如何，我會把它放在一個init方法中，看看它是否有任何作用。奇怪的是，它不適用於單一類的情況。它適用於其他人。

來源

2011-02-02 Chris Dennett

回答

0

通過將安裝程序移動到init方法解決了這個問題，結果發現在構造函數中執行所有操作時出現了一些奇怪現象。因此，當我嘗試訪問它們時，爲什麼Atomic *字段爲空。發生這種情況的原因是，自從超級調用父構造函數之後，它們還沒有被設置。爲什麼其他元素是好的，超出了我的意思，但是這固定了它。

來源

2011-02-04 04:35:23

1

輸出有些奇怪：以ahaaaa2作爲前綴的行看起來是在以ahaaaa1爲前綴的行之前打印的。但實際上，ahaaaa2行來自以前的一組值，而ahaaaa1行來自下一組值。

以ahaaaa1爲前綴的行是具有默認值（0）的行。正如我所預料的那樣，ahaaaa2的行似乎具有正確的值。我想如果你在System.out.println("ahaaaa2:: " + this.toString())之後加了一兩個換行符，你會發現輸出是正確的。

編輯：OK，我終於看到了問題。在輸出的最後一行（非常難以閱讀！）結束時，您再次打印所有統計數據。當你希望看到這一點：

FlowStats/[email protected][flowId: 4, packets: 4, bytes: 762, delayFromFirstProbeSum: 0]

你，而不是得到：

FlowStats/[email protected][flowId: 0, packets: 0, bytes: 0, delayFromFirstProbeSum: 0]

等爲其他FlowProbeFlowStats對象

我沒有一個線索，這是怎麼回事，但我也沒有看到最終生成線的位置，以及FlowProbeFlowStats對象在此期間可能發生的情況。沒有看到更多的代碼，我不認爲我可以提供幫助。

來源

2011-02-02 20:52:04

+0

如果您在第二個代碼塊中看到1和2變量是成對的。在設定操作完成後，我只是聲稱這個狀態。奇怪的是，混亂的類變量只能在構造函數中完成，並且這些字段在其他情況下是隱藏信息的。沒有固定器或清晰的方法。所有這些都在一個循環線程中完成，並且這些對象在迭代之間不會被重用。 – 2011-02-02 23:47:24

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